Kerbal Space Program

Even a little electrical whine would make it so much better, it's just so quiet and dull otherwise; the music isn't enough.

Might have to account for the vacuum, or adjust volume according to air pressure/air speed. Can't hear much when going fast in the wind, can you? The sound of the wind muffle other sounds, and the sound might not even reach you if you're faster than the sound itself.

It might be nice if the Doppler effect was implemented as well, too. Like going for realism..